We are studying the regulation of the MAL6 gene complex of yeast. Our long-term goal is to develop a complete description of all the components of this complex regulatory system. In this proposal we focus on the role of the major regulatory protein coded by the MAL63 gene. We intend to study its interaction with its promoter and other components of the regulatory apparatus, and ultimately to determine the mechanism by which it activates transcription. Initiation of mRNA synthesis is a fundamental control point in the regulation of gene expression. The frequency of initiation ultimately depends on the interaction of the proteins of the transcription apparatus with each other and with specific DNA sequences. While it is traditional to discuss separately transcriptional initiation in bacteria, the lower eukaryotes, and the higher eukaryotes, it has become increasingly clear that analogous mechanisms are involved. In this proposal we intend to use yeast as a model for transcriptional regulation in eukaryotes. In particular we intend to establish, using both biochemical and genetic techniques, the nature of the interaction between a yeast activator protein, its controlling sequences, and other components of the regulatory system.